In vivo assessment of safety and mechanisms underlying in vitro relaxation induced by Mikania laevigata Schultz Bip. ex Baker in the rat trachea

Safety evaluation of Mikania glomerata and Mikania laevigata in healthy volunteers: A randomized, open label and multiple dose phase I clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Mikania glomerata (MG) and Mikania laevigata (ML) leaves are used interchangeably in Brazilian ethno-medicine, mainly for the treatment of respiratory diseases, but there is no clinical trial for the safety evaluation of these species at different doses.

AIM OF THE STUDY

To evaluate the safety of two oral solutions from each species, across two weeks of use and two doses.

MATERIALS AND METHODS

A randomized, open-label, multiple dose, two-arm trial. Participants (n = 19) were randomly allocated to one of the arms of the trial. Group 1 received 15 mL of MG oral solution twice daily for 7 days and then 30 mL twice daily for 7 days. Group 2 received ML oral solution in the same manner. After 14 days, the participants went through a washout period of 7 days before cross-over to the other group. Adverse events (AEs), clinical parameters and blood markers were monitored at the beginning (T0) and at the end of each week of the study, which was concluded after six weeks. AEs were classified as mild, moderate or severe, and according to their correlation with the medicine intake, the measured parameters were compared to T0 by generalized estimating equations (GEE) to determine those affected by the use of the oral solutions (p < 0.05).

RESULTS

MG was not correlated to any of the reported AEs; its use affected three of the evaluated parameters: total protein, diastolic blood pressure and urea, although all the changes were within the normal range for healthy individuals. ML was correlated to one moderate AE of pyrosis and the alteration of 12 parameters: erythrocytes, hemoglobin, hematocrit, monocytes, time of prothrombin, time of thromboplastin, albumin, alkaline phosphatase, total protein, urea, potassium and sodium. All changes were within the normal range for healthy individuals.

CONCLUSION

ML and MG are considered safe for humans under the dose regimen tested.

Toxic Potential of Cerrado Plants on Different Organisms

Cerrado has many compounds that have been used as biopesticides, herbicides, medicines, and others due to their highly toxic potential. Thus, this review aims to present information about the toxicity of Cerrado plants. For this purpose, a review was performed using PubMed, Science Direct, and Web Of Science databases. After applying exclusion criteria, 187 articles published in the last 20 years were selected and analyzed. Detailed information about the extract preparation, part of the plant used, dose/concentration tested, model system, and employed assay was provided for different toxic activities described in the literature, namely cytotoxic, genotoxic, mutagenic, antibacterial, antifungal, antiviral, insecticidal, antiparasitic, and molluscicidal activities. In addition, the steps to execute research on plant toxicity and the more common methods employed were discussed. This review synthesized and organized the available research on the toxic effects of Cerrado plants, which could contribute to the future design of new environmentally safe products.

A kinetic study of the main guaco metabolites using syrup formulation and the identification of an alternative route of coumarin metabolism in humans

For decades guaco species have been empirically used for the treatment of respiratory diseases. However, studies have shown that the toxic and therapeutic effects of the main guaco metabolites are dose-dependent, and none clinical study was done to evaluate the behavior of these substances in humans. In this work, a pilot study measuring the kinetic profile of the main guaco metabolites was performed leading to the knowledge of an alternative route of coumarin metabolism in humans. Initial screenings demonstrated that the administration of 60 mL of guaco syrup (single dose) did not provide sufficient levels of coumarin (COU), 7-hydroxycoumarin (7-HCOU), o-coumaric acid (OCA) and kaurenoic acid (KAU). The pharmacokinetic parameters were calculated by orally administering 60 mL of guaco syrup spiked with 1500 mg of COU. The kinetic study demonstrated that the plasmatic levels of 7-HCOU (considered the main metabolite of COU) were 10 times lower than the levels of COU, and the kinetic profile of 7-HCOU suggests sequential metabolism in the liver with low access of 7-HCOU to the systemic circulation. The study also demonstrated that OCA is one of the main bioavailable metabolites of COU. Therefore, the hydrolysis of the lactone ring forming a carboxylated compound is one of the possible routes of COU metabolism in humans. The half-lives of COU, 7-HCOU and OCA were approximately 4.0, 1.0 and 3.0 h, respectively and there was evidence that the recommended dosage of guaco syrup did not provide sufficient levels of COU, 7-HCOU or OCA to obtain a bronchodilation effect. Clinical studies are necessary to prove the efficacy and safety of products based on guaco.

Development and validation of two methods based on high-performance liquid chromatography-tandem mass spectrometry for determining 1,2-benzopyrone, dihydrocoumarin, o-coumaric acid, syringaldehyde and kaurenoic acid in guaco extracts and pharmaceutical preparations

In this study, two HPLC-ESI-MS/MS methods were developed and validated for the determination of 1,2-benzopyrone (COU), o-coumaric acid (OCA), kaurenoic acid (KAU), syringaldehyde (SYR), and dihydrocoumarin (DIH) in guaco extracts and pharmaceutical preparations (syrup and oral solution). The chromatographic separation was achieved using a C18 XBridge 150×2.1-mm (5-μm particle size) column maintained at 25°C. The mobile phases consisted of a gradient of water and acetonitrile containing 0.05% formic acid or 5  mM ammonium formate for the positive and negative ion modes, respectively. All of the calibration curves showed excellent coefficients of correlation (r≥0.9970) over the ranges of 1.25-400  ng/mL for coumarin, 10-600  ng/mL for dihydrocoumarin, 5-250  ng/mL for KAU, and 25-500  ng/mL for o-coumaric acid and syringaldehyde. The range of recovery was 96.3-103% with an RSD% of <4.85% for intraday and interday precision. The results indicate that the developed methods are fast, efficient, and sensitive for the quantification of the guaco metabolites in extracts and pharmaceutical forms while avoiding purification and derivatization steps.

Scientific evidence for Mikania laevigata and Mikania glomerata as a pharmacological tool

OBJECTIVES

Historically, the majority of new drugs have been generated from natural products as well as from compounds derived from natural products. In this context, Mikania laevigata and M. glomerata, popularly known as 'guaco', have a long history of use. Brazilian Indians have an ancient tradition of using 'guaco' for snakebites. In current herbal medicine in Brazil, 'guaco' is used as an effective natural bronchodilator, expectorant and cough suppressant employed for all types of upper respiratory problems including bronchitis, pleurisy, colds and flu, coughs and asthma.

KEY FINDINGS

In Brazil, this plant has been widely used, even as commercial preparations. Its medicinal properties are widely recognized, mainly in the treatment of inflammatory conditions, bronchodilator activity, anti-ulcerogenic, antiophidian as well as antibacterial and antiparasitic activity, although the efficacy of the antibacterial activity is so far controversial.

SUMMARY

The studies on Mikania glomerata and M. laevigata have provided scientific evidence that those plants have a considerable anti-inflammatory therapeutic potential.

Relation between statistics and treatment-related changes obtained from toxicity studies in rats: if detected a significant difference in low or middle dose for quantitative values, this change is considered as incidental change?

The purpose of a toxicity test is to determine the no-observed-effect level (NOEL) of test substance through biological and pharmacological techniques. If the low dose not does show statistically significant and biologically relevant changes in the data evaluated in a study, the usual practice is to consider this dose as the NOEL. To overcome this, 6 types of techniques that seemed to be appropriate are presented in this paper by investigating the results of several domestic and foreign theses on toxicology. The most appropriate techniques appear to be the trend test, comparison between treatment group and historical control by t-test, and confirmation that all individual values lie within the 95% confidence interval (2 SD) of the historical control value, if a significant difference is admitted in the low dose.